Having dismantled my layout, I'm building a small inglenook style shunting puzzle.

The required stock will be fitted with Kadee couplings to allow hands-free uncoupling but I'm not sure what type of magnets I need.

I remember some experiments posted on here several years ago but either I can't find the thread or it's been lost in the mists of time ….

Does anyone use neodymium magnets for this purpose and if so, what size, strength and position are they please.

It is OO gauge.

After a bit of searching Peter, I've found Perry's original thread plus a couple of others.

Kadee magnetic uncoupling – Your Model Railway

Uncoupling with Neodymium magnets – Your Model Railway

Looks like I was using square magnets back in 2017 and my N gauge layout uses Kato uncoupling tracks.

Shunting Puzzle Plank – Your Model Railway

Haven't got around to trying out the Dapol Easi-Fits yet, which are very similar.

Another one here.

Operation Abyss – Your Model Railway

Not sure about the strength, but if you read throught it must be mentioned somewhere.




 

That's brilliant Ed - thanks a million !

Perry's thread was the one I remembered but couldn't find it (nor could I remember his name !! )

I'll have a read through and hopefully, get some answers.  Obviously I don't want to start a magnet store so if I can find the right one first time, I'll be laughing ……

Having spent some time (actually, a long time) reading through these threads, I'm going to have a bash with Perry's 5 magnet system and hope I can get as good results as he did.

I've ordered a lorry load of neodymiums - the more one buys, the cheaper they seem to be.  I ordered from a French site - 'Supermagnete.fr'  which seemed to offer a decent range at a sensible price.  This, it appears, is the french version of a German company, 'Webcraft GmbH' but their German site wanted €18 for delivery !!

Once the magnets arrive, I'll get the glue out and do some experiments ………………………..fingers crossed.  If it doesn't work, let me know if anyone needs any tiny magnets …………?  

If I remember correctly, it was getting the height of the magnets below the rails that was the tricky bit.
 

If I read it properly Ed, the whole thing is tricky …………………..

We'' see - the magnets are due to be dispatched on Monday - I didn't go for "rush" postage …………………

Well the magnets arrived, very well packaged and sent direct from Germany !!!

I'd ordered some 3mm cubes, some 5mm diameter cylinder magnets and they sent me, as a gift, some tiny rectangular magnets - 5mm x 2.5mm x 2mm.

The 3mm cubes apparently had a pulling power of 290 g, the 5mm cylinder, 940g and the tiny rectangular ones an amazing 450g.  The cubes and cylinders wewre magnetised to N45 and the small rectangles to 44H.

Having done some elementary and somewhat rushed testing, I found the cube magnets, as used by Perry - 5 in a row between the rails,  had very little effect.  It could be that they were set too low down, the Kadees weren't properly adjusted.  I then tried the cylinders using 2 end to end outisde the track but close to the outer edge of the rails.  That worked perfectly - in fact, perhaps too perfectly in that the Kadees 'snapped' open.  I then tried the same 2 magnets but set into the baseboard between the rails.  That also worked well and presented les of a 'snap' than with them being outside the rails.  Thet's understandable given that in this situation, the magnets were almjost underneath the coupling tails.  I'll do further research to see if a single cylinder will work or if altering the height of the cubes makes any difference …………….

Don't go away …………………………………………….

Petermac, I use the 3mm cubes, 5 in a row with 3 rows between  sleepers  & level with the top of adjacent sleepers& they work - one row is not enough magnetic spread for the tails of the couplers  but then whatever works for you - yep go for it !

Thanks Sol.  I only put a single row of 5 in place as a quick test.  I think they were perhaps slightly lower than the sleeper top but, in most cases, there was hardly any movement at all from the Kadees.  I'll give it another shot with extra rows and see what happens.

I wonder if the strength of your (and Perry's) magnets is more than mine - I think Perry got his from China, mine came from Germany but they may have a lower 'pull' than others.  As I said, the 'lift' of the cubes was stated as 290 gms whereas the cylinder ones had more than 3 times the 'lift' at 940 gms.  I have no idea what effect adding more magnets has on the total lift - is there a scientific formula ?